Thanks Bnut.
Busy day, I'll respond with more later. I'll will say that congress did indeed ban ALL exports.
Will
No rush, it isn't really a contest

I enjoy these trivia/history subjects. I wouldn't be as interested if I hadn't just read a couple of books on the Revolution

Trade importance varied by year as well as by trade partner. During times of war, certain comodities were highly valued, etc. For example, during the 7 Years War (French/Indian War), imports to the colonies actually increased by 50% or more, due simply to war supplies being shipped in. Britain had a robust fisheries business, so they did not import much fish, however S. Europe and the West Indies had a high demand for colonial fish (dried).
Just to give you a sense, in 1770, here were the top EXPORTS from the colonies (to all countries)(number in parentheses is % of total value in pounds sterling). These goods in aggregate made up approx. 75% of the value of all EXPORT trade:
Tobacco: 27.0%
Bread & Flour: 15.0%
Dried Fish: 11.2%
Rice: 10.2%
Wheat: 3.9%
Indigo: 3.9%
Furs: 2.7%
Compare those categories to the categories for lumber and wood goods:
Pitch, Tar, Turpentine, Rosin: 1.0%
Masts, Yards, etc: 0.5%
Pine, Oak, Cedar lumber (finished boards): 1.7%
Pine, Oak timber (incl. framed houses): 0.3%
Staves, heading and finished barrels: 2.1%
So the colonies exported 4x the value in barrels as they did in spars

(Barrels were critically important back then for shipment and storage). This may not tell the complete story, of course. Masts and spars may not have been a big business, but though small may have been uniquely important (if those masts and spars could not be obtained elsewhere).
This may help to explain why, at least in traditional history books, you read so much about Tobacco, Farm Goods, Sugar, Tea, and English Manufactured Goods. These categories represented over 60% of the import/export balance between England and the Colonies. (This is before the rise of the whaling and cotton industries).